Bioaccumulation of POP's in Humpback Whales

The Humpback whale is an endangered species.  There are around 10,000 to 15,000 of them world wide. This whale can be found in all of the words oceans and they make seasonal migrations for feeding and breeding.  During the winter months, the whales travel to the warm tropical waters to breed.  It takes a female 11-12 months to develop the calf before it is born.  After the calf is born it consumes around one hundred pounds of milk a day from its mother and stays with her for about a year.  It will take a whale 15 years to fully mature.  During the summer months, the whales travel to the cold arctic waters to feed.  In these cold waters they consume about 1 ton of food daily.  The feeding season lasts for 120 days and then the whales live off of stored fat for the remaining seasons.  These mammals can live up to be 45-50 years old.  Since the Humpback whale is such a long lived animal, it makes them the perfect bioindicator.  Humpback whales have been used in studies to determine the concentrations of persistent organic pollutants found in their body and also in the different feeding areas of the whales.  While consuming small fish, crustaceans, and plankton, the whales are also consuming small concentrations of persistent organic pollutants (POP’s).  POP’s are compounds that do not degenerate in the natural environment and build up in systems.  This build up of the POP’s introduces the concept of bioaccumulation, which is the intake of an organic compound at a higher rate than the rate that it is leaving the system.  The POP’s are entering the marine systems through run off, waste, and atmospheric pollution.  With the help of currents and the Westerlies these pollutants are carried and spread at a global scale.  

 In a study the blubber of humpback whales was sampled from male whales at various feeding locations in the Pacific and Atlantic Ocean.  A chromatography test was then run test for the following POP’s: PCB’s, DDT, Chlordanes, PBDE’s, and HCH’s.  The goal of this study was to see if these pollutants were present in higher concentrations in certain feeding locations and if the concentrations of these pollutants were of any harm to the whales.  The studied showed that the North Atlantic contained the most contaminants and the Gulf of Maine specifically had significantly higher concentrations than the other areas tested (Elfes, et. al, 2009).  These high concentrations were thought to be caused by the increased industrialization and the increased population size (Elfes, et. al, 2009).  The difference in results could also be caused by change in prey found in the different feeding locations; for example the whales feeding in the North Atlantic could be consuming prey of a higher trophic level than those whales feeding in the Pacific (Elfes, et. al, 2009).  Also from these results another observation was made.  A positive correlation between the age and concentration was found.  With the increase of whale age there was an increase of the concentrations of the POP’s (Elfes, et. al, 2009).  This was perfect correlation to represent the bioaccumulation of the POP’s in the humpback whale.    

Another study also wanted to test the concentrations of POP's in the humpback whale.  Instead of focusing on the feeding locations and age, the test compared the concentrations of the POP’s found in female whales to those found in the calves.  The goal of this was to see if the female whale transferred some of her concentrations to the calf during the offspring development (Metcalfe, et. al, 2003).  The concentrations of the two were found to be very similar in each of the POP’s tested for, with no significant difference (Metcalfe, et. al, 2003).  Since there was no significant difference in the concentrations of the pollutants found in the female and calf, it was predicted that the female whale does in fact transfer it’s contaminants to the calf (Metcalfe, et. al, 2003).  It was stated that this could be possible through transplacental and lactational transfers (Metcalfe, et. al, 2003).               

Although there were pollutants found in all of the blubber samples, the concentrations present were not at threatening levels to the whales.  But it is a prefect example that POP’s do not degenerate and remain in the environment for decades.  Even though several of the POP’s have been banned from use it does not mean that they do not exist in the environment.  In fact as the economy grows, new pollutants are being introduced into the environment.  Since the humpback whale is an endangered species, it is important to continue to monitor these concentrations in order to ensure that no unnatural harm is being exposed to the whales.